Strong healthy bones are less likely to break and fracture than weak ones. As we age, our bones naturally weaken due to hormonal and chemical changes in the body that tend to make us deficient in the mineral calcium.

Calcium is essential to bone strength. Yet you can consume massive amounts of calcium and still come up short. Why? It's because calcium works with vitamin D to make the bones strong, and it could be that you don't have enough vitamin D.

Michele Bellatoni, director of Geriatric Medicine and Gerontology at Johns Hopkins Bayview Care Center, said the mix is important to save off osteoporosis and fractures.

She spoke with physicians at King Edward VII Memorial Hospital recently as part of a continuing education programme.

In the US, women 65 and older are screened for bone weakening. Women at risk – those with a family history of osteoporosis or those who smoke – should be screened at 60.

"We did a study that showed that 95 percent of the elderly population that came to the emergency ward at Johns Hopkins were deficient in vitamin D and calcium," she said. The study also showed that the five percent not lacking vitamin D and calcium were getting it through supplements.

Dr. Bellatoni said there are several reasons for the deficiency.

n We each need at least ten minutes of direct sunlight on the face every day to produce enough energy for the skin to metabolise vitamin D. Although you may feel energised and even hot sitting by a sunny closed window, Dr. Bellatoni said the glass is blocking the rays you need. Similarly, while skin cancer awareness campaigners stress the use of sun-block products, Dr. Bellatoni said such products also block the energy required to metabolise vitamin D. Protective clothing and other paraphernalia we use to give us shade, like umbrellas and caps, also shield us from necessary sun energy. "As part of our daily routines, we've found that people just don't get enough sun," she said.

n Prescription antacids as well as over-the-counter products like Tums, Rolaids and baking soda impair the absorption of vitamin D, which leads to calcium deficiency.

n All carbonated beverages, even fizzy waters like Perrier, affect calcium absorption. According to Dr. Bellatoni, phosphates in these drinks have a chemical reaction with calcium in the body. The phosphates bind to the calcium molecules.

This binding ties up the dietary calcium making it unavailable to be absorbed. "I see sodas the way I see cigarettes," she said. "We used to think it was fine to smoke, but learned the health risks and have changed our view. We need that type of change in culture to use [still] water."

Dr. Bellatoni said in many cases women who have been advised to take calcium supplements do not because it causes bloating and makes them gassy. She advised that taking calcium supplements with acidic juices like orange and grapefruit, will help counter those effects.

Failure to get sufficient quantities of calcium and vitamin D is likely to result in weakened bones sooner in a person's life.

Dr. Bellatoni said nuisance fractures – like those of the wrists or ankles – are a strong indicator that the person will go on to suffer a hip fracture. Those who suffer from them should have a bone density test in an effort to prevent debilitating hip fractures.

US physicians also use the fracture risk assessment tool or FRAX – the World Health Organisation standard – for determining osteoporosis. It predicts a patient's likelihood of fracture in ten years and is accessible online.

Dr. Bellatoni said more accurate results are achieved when a bone density figure can be entered in the equation.

"In the US we begin prescription medication when the ten-year risk of fracture is ten percent," she said.

For those with other risk factors like family history and smoking, Dr. Bellatoni said US doctors start medication when the ten-year risk of fracture is at 20 percent.